Tube



FIG. 1 is a top perspective view of a tube in accordance with my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a side elevational view thereof; and,

FIG. 4 is a bottom plan view thereof.

The broken lines in the figures are for the purpose of showing unclaimed environmental structure only and form no part of the claimed design. 

CLAIM The ornamental design for a tube, as shown and described. 